The present invention relates to a method and apparatus for pumping oil or other subsurface fluids from a well.
Pumping of oil and other fluids from relatively small wells is conventionally practiced using what is commonly referred to as a pump jack or walking beam apparatus. The walking beam is operated to reciprocate a sucker rod extending downwardly into the well casing and which is connected at its lower end with a downhole or deep well pump. Reciprocating the sucker rod actuates the downhole pump and results in an upward pumping of the oil through the well casing.
The walking beam essentially comprises an arm or beam pivotally mounted substantially perpendicular to the sucker rod and connected therewith at the upper end of the sucker rod remote from and externally of the well casing. Since the sucker rod may extend 3,000 feet or more to the bottom of the well casing, the same has considerable mass and reciprocating the sucker rod consequently requires a relatively large and heavy walking beam arm as well as a substantial source of power for moving the same. Operating such large mechanisms clearly necessitates the expenditure of considerable amounts of energy and can be dangerous to people working in the area and damaging to the immediate environment.
The size of the pump jack or walking beam mechanism utilized in connection with a well is selected according to the depth of the wall; the deeper the well, the larger the size of the pump jack. Should pumping operation of the well indicate that its depth must be increased for maximum return of oil, it might be necessary to replace the walking beam with another at great cost and with a significant loss of pumping time and consequently of oil recovery.
In addition, use of a walking beam apparatus requires that the same be initially ground-levelled relative to the well casing so that when the beam's pivoting arm reciprocates the sucker rod, maximum moving force is transmitted from the beam by way of a direct center line or axial pull on the sucker rod. Relatively minor misalignment may result in, inter alia, breakage of the sucker rod within the well casing where the break is difficult to locate and to reach for repair, degeneration of the various well closure and anticontamination seals and consequent scoring of moving portions of the pumping apparatus including the polishing rod associated with the sucker rod, and possible damage to the well casing and head. This alignment problem is particularly important because ground movement as by shifting or swelling often occurs during subsurface fluid pumping, causing angular or lateral shifting or bending of the well casing. In such cases, pumping operations must be halted while the walking beam is relevelled and rebalanced so as to prevent breaking of the sucker rod which is otherwise likely to occur. Halting of pumping, due to sucker rod breakage or the need to remount or rebalance the pump jack, is extremely costly to the well owner or operator.
It is the desideratum of the present invention to provide a pumping rig for supported connection with the well casing of an oil well to enable the pumping rig to automatically remain aligned with the well casing in the event of angular or lateral shifting of the well casing and thereby prevent breakage or rupture of the operating mechanism of the pumping rig caused by non-alignment therewith.
In particular, it is an object of the present invention to provide an oil pumping rig in which the axial alignment of the sucker rod relative to the well casing is automatically maintained should the position of the well casing shift.
It is another object of the present invention to provide a pumping rig in which the sucker rod is supportedly suspended at its end remote from the well casing and is unconnected with the rig at any other point along the length of the sucker rod.
It is a further object of the present invention to provide a pumping rig in which the reciprocally movable sucker rod is relatively laterally spaced from the rig along its entire length other than at a single connection with an actuating means for reciprocating the same so as to permit the sucker rod to flex, distort or move laterally and to bend along its length without constriction.
It is still another object of the present invention to provide a fluid-operated pumping apparatus for actuating deep well pumps which is compact, portable and relatively inexpensive to manufacture and operate.